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Discuss Simple question about installing motion sensor in the Electrical Forum area at ElectriciansForums.net

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Freeb0

New EF Member
Hello,

I have a simple problem, but I can't seem to find how to solve it. I hope someone here can help me out.

I have a lamp that is connected to 2 light switches. I wanted to replace 1 light switch with a motion sensor. In the previous switch 2 black cables arrived and 1 grey cable left.

First I bought a motion sensor which couldn't handle the low wattage of my LED bulb. I figured out my mistake and bought the correct one.

Now the problem is that the light sensor only has 1 entry and 1 exit. I tried each of the cables in every configuration, I even tried putting both black cables together in the motion sensor as well as the grey one but nothing seems to work. The light turns on and then never turns off again.

Does anyone know what I am doing wrong here?

Thanks!
 
A

Adam W

You could have wired it up wrong, the settings on the sensor could be 'wrong' or despite what you say it may not be the correct type of sensor.
 

Spoon

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I have a lamp that is connected to 2 light switches. I wanted to replace 1 light switch with a motion sensor. In the previous switch 2 black cables arrived and 1 grey cable left.
Welcome to the forum mate.
This is what I think:
The light switches you have are currently 'change over' switches (Common, L1, L2). As you have 2 switches to activate 1 light these are used.
Your sensor just has a Normally Open contact. Looks like you have got the wrong sensor. I presume they do sensors with 'change over' switches....
 

ElectroChem

Industrial Controls Electrician
Welcome to the forum mate.
This is what I think:
The light switches you have are currently 'change over' switches (Common, L1, L2). As you have 2 switches to activate 1 light these are used.
Your sensor just has a Normally Open contact. Looks like you have got the wrong sensor. I presume they do sensors with 'change over' switches....
Even then, you couldn't just whack in a sensor in place of a 2-way switch, or any time you actuated the physical switch you'd reverse the contact polarity of the sensor. The circuit needs to be rewired to a parallel double switched I would think.
 

Spoon

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The circuit needs to be rewired to a parallel double switched I would think.
If you did this and used the light switch then the sensor would not change the state of the light. The light would always be on, if the light switch was on.
 

Wilko

Electrician's Arms
Hi - you may need N at the motion detector, is there one at the switch? Pic of the detector wiring instructions would clarify (for me anyway:)).
 
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ElectroChem

Industrial Controls Electrician
If you did this and used the light switch then the sensor would not change the state of the light. The light would always be on, if the light switch was on.
Indeed, otherwise you would turn the light on at the switch then the sensor would turn it off! I can think of no reason why you would put a PIR in a 2-way switching arrangement, but I'm just a poor industrial controls boy, the mysteries of houses are beyond me.
 

Spoon

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.. but I'm just a poor industrial controls boy, the mysteries of houses are beyond me.
Nothing wrong in that mate.... proper electrics.. :) Just stick the signals into a plc and then you can do anything you want with the light.. Job done.. :tearsofjoy:
 
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